1. Field of the Invention
This invention relates to medicators for effecting injections of medicaments and the like, particularly by the use of needleless pyrotechnic-powered injectors but also by the use of conventional syringes.
More particularly, the invention relates to a device for rapidly and easily but very accurately filling such medicators with medicament.
The invention is particularly directed toward use by lay people who are not medically trained and who may, by infirmity due to old age or otherwise, not have full muscular control for fine movements or sharp vision for reading fine volume-calibration scales as on syringes--but who must nevertheless regularly medicate themselves by injections at home. Elderly diabetic outpatients constitute a particularly numerous example.
The invention is also particularly directed toward use by medical professionals for certain specialized applications:
(1) filling needleless injectors, or disposable ampules for such injectors--because neither the injectors nor the disposable ampules are adapted for suction filling as are syringes;
(2) filling syringes in circumstances requiring extremely precise dosages or very precise mixing of different medicaments within a single syringe; and
(3) filling needleless injectors, disposable ampules, or syringes with medicaments which are unstable in solution and must be ready-mixed at the time of use.
Examples of medicaments mentioned in the third category are the many lyophilized solutes to which a diluent is added just before use. Further, readily soluble medicaments might be marketable in a dry storage form to enhance shelf life and diminish reactivity problems--and immediately before use dissolved and by means of the present invention loaded into an injection device.
Needleless injectors and disposable ampules are preferably fillable from bulk supply by some procedure which is not limited to a factory or specially equipped laboratory. In particular it is desirable that the device be conveniently fillable by shut-in patients at home, pharmacists in neighborhood dispensaries, paramedics, country doctors, wilderness rescue teams, physicians serving battlefield camps, disaster areas or primitive societies, and other remote users.
2. Prior Art
We know of no prior devices for performing the filling operation described above under the particular constraints mentioned.
Hypodermic syringes of the many sorts with which our invention would be compatible are of course thoroughly familiar devices. Needleless pyrotechnically powered injectors are much less familiar articles to the general public, but are becoming well-known to medical professionals; the state of the art as to such devices may be noted by reference to our U.S. Pat. Nos. 4,089,334, which issued May 16, 1978 under the title "Pyrotechnically Powered Needleless Injector," and 4,124,024, which issued Nov. 7, 1978 with the title "Disposable Hypodermic Injection Ampule."
The first of these patents discloses an integral injecting device accommodating an aliquot or dose of medicament, a pyrotechnic or deflagratory charge capable of propelling the medicament through a fine orifice into a patient, a piston for isolating the medicament from the charge, means for igniting the charge, and a housing which brings the various components together in appropriate relationships.
The second of our patents discloses a modification in which the medicament, pyrotechnic charge and piston are in a separate, disposable module, referred to as an "ampule."
The filling procedure normally used for syringes is not only (as already mentioned) inapplicable to needleless injectors or their disposable ampules; it also has serious limitations even as used for syringes. Hypodermic syringes are conventionally filled by immersing the end of the needle in the medicament and pulling the handle outward, while observing the fluid level in the syringe against the volume scale on the syringe wall. This operation requires a certain amount of manual dexterity or at least steadiness, as well as visual acuity.
The present invention makes pyrotechnic injectors and ampules conveniently fillable in homes, pharmacies and field use; and greatly facilitates the refilling of conventional syringes of virtually any type.